Papers by Alberto Toxqui Terán
Waste and Biomass Valorization, 2021
In the last decade, considerable landings of pelagic Sargassum (a kind of brown algae) have been ... more In the last decade, considerable landings of pelagic Sargassum (a kind of brown algae) have been recorded in several Atlantic countries, affecting coastal ecosystems and producing important losses to the region’s economy. Massive landings of Sargasso could become an annual event on different grades from now on. Here we present a potential solution for rapidly managing the Sargasso avoiding the production of the characteristic fetid odor and reduces pollution. By direct combustion the Sargasso can provide 12.94 MJ/kg (11.6% moisture), minimizing considerably the volume of the brown algae, along with the production of a small amount of syngas (23%) when the Sargasso is heated in a reducing atmosphere. Invariably, between 14–18% of ash will be produced by burning the biomass. Then, we propose the valorization of the residual ash (mainly composed by CaO) by carbon dioxide mineralization to produce calcium carbonate. This would allow us to reutilize a material considered a pollutant; where 440 g of CO2 per kg of highly pure floated calcium carbonate would be consumed. This will lead to a reduction of CO2 emissions and residual ash ending in landfills.
Waste and Biomass Valorization, 2021
In the last decade, considerable landings of pelagic Sargassum (a kind of brown algae) have been ... more In the last decade, considerable landings of pelagic Sargassum (a kind of brown algae) have been recorded in several Atlantic countries, affecting coastal ecosystems and producing important losses to the region’s economy. Massive landings of Sargasso could become an annual event on different grades from now on. Here we present a potential solution for rapidly managing the Sargasso avoiding the production of the characteristic fetid odor and reduces pollution. By direct combustion the Sargasso can provide 12.94 MJ/kg (11.6% moisture), minimizing considerably the volume of the brown algae, along with the production of a small amount of syngas (23%) when the Sargasso is heated in a reducing atmosphere. Invariably, between 14–18% of ash will be produced by burning the biomass. Then, we propose the valorization of the residual ash (mainly composed by CaO) by carbon dioxide mineralization to produce calcium carbonate. This would allow us to reutilize a material considered a pollutant; where 440 g of CO2 per kg of highly pure floated calcium carbonate would be consumed. This will lead to a reduction of CO2 emissions and residual ash ending in landfills.
Carbohydrate Polymers, 2021
Better understanding through direct observation of the mechanisms involved in chemical and enzyma... more Better understanding through direct observation of the mechanisms involved in chemical and enzymatic hydrolysis of biomass is of great importance, to implement a substitute for the common cellulose standards. We report the hydrolysis of biomass, using exclusively the parenchyma, to isolate cellulose nanoplatelets using a less harsh pretreatment. Then, we show direct evidence of the effect of endoglucanase on the structure of cellulose nanoplatelets, finding that amorphous cellulose is exclusively digested, loosening the cellulose nanofibrils in the process. The analysis of micrographs demonstrates that when cellulose nanoplatelets are deposited on a silicon wafer, its thickness can be qualitatively measured by the interference color detected using an optical microscope. This finding facilitates further studies of mechanisms involved in lignin removal and cellulose nanofibrils production by specific enzymatic digestion.
Carbohydrate Polymers, 2021
Better understanding through direct observation of the mechanisms involved in chemical and enzyma... more Better understanding through direct observation of the mechanisms involved in chemical and enzymatic hydrolysis of biomass is of great importance, to implement a substitute for the common cellulose standards. We report the hydrolysis of biomass, using exclusively the parenchyma, to isolate cellulose nanoplatelets using a less harsh pretreatment. Then, we show direct evidence of the effect of endoglucanase on the structure of cellulose nanoplatelets, finding that amorphous cellulose is exclusively digested, loosening the cellulose nanofibrils in the process. The analysis of micrographs demonstrates that when cellulose nanoplatelets are deposited on a silicon wafer, its thickness can be qualitatively measured by the interference color detected using an optical microscope. This finding facilitates further studies of mechanisms involved in lignin removal and cellulose nanofibrils production by specific enzymatic digestion.
Polymers, 2022
A functional food based on blends of carbohydrate polymers and active ingredients was prepared by... more A functional food based on blends of carbohydrate polymers and active ingredients was prepared by spray drying. Inulin (IN) and maltodextrin (MX) were used as carrying agents to co-microencapsulate quercetin as an antioxidant and Bacillus clausii (Bc) as a probiotic. Through a reduced design of experiments, eleven runs were conducted and characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), and modulated differential scanning calorimetry (MDSC). The physical characterizations showed fine and non-aggregated powders, composed of pseudo-spherical particles with micrometric sizes. The observation of rod-like particles suggested that microorganisms were microencapsulated in these particles. The microstructure of the powders was amorphous, observing diffraction peaks attributed to the crystallization of the antioxidant. The glass transition temperature (Tg) of the blends was above the room temperature, which may promote a higher stability during storage. The antiox...
Waste and Biomass Valorization, 2021
The Journal of Physical Chemistry C, 2017
Journal of Food Process Engineering, 2015
In this work was studied the effect of the degree of polymerization (DP) in two systems based on ... more In this work was studied the effect of the degree of polymerization (DP) in two systems based on inulin. Understanding the relation between the chemical and physical properties, allows establishing the potential application for inulin according to its DP. Amorphous inulin powders were characterized by mass spectrometry to determine the DP. Inulin from chicory root and dahlia tubers showed a DP of 2–15 and 2–12, respectively. The systems were exposed to different water activities, finding sigmoidal curves type II. Thermal analysis showed two melting events, suggesting the presence of crystals differing in size. The glass transition temperature range widened and lowered in the high DP inulin. By X-ray diffraction low DP inulin presented a moderate transition behavior while in high DP inulin was conducted abruptly. State diagrams for stability showed that high DP inulin must be stored at more rigorous conditions of temperature and humidity for avoiding unwanted crystallization effects. Practical Applications The results presented in this work are useful for: (i) relating the physical and thermal properties (Tm, Td and Tg) with the degree of polymerization of sugar-rich systems such as inulin powders, (ii) set the optimal processing conditions in an industrial application such as spray drying process while avoiding product damage, and (iii) predicting the product stability based on the physical properties plotted in the form of a state diagram.
Materials Letters, 2012
ABSTRACT Co 2 SnO 4 powders with the spinel structure were successfully obtained by the sol–gel m... more ABSTRACT Co 2 SnO 4 powders with the spinel structure were successfully obtained by the sol–gel method using Co(NO 3) 2 ·6H 2 O and SnCl 4 ·5H 2 O as raw materials, followed by calcining at 900 and 1500 °C for 1 h. Charac-terization by XRD and SEM showed that at 900 °C, crystalline spinel accompanied by Co 3 O 4 and SnO 2 is obtained, while at 1500 °C homogeneous single-phase spinel powders are synthesized. Analysis by X-ray dif-fraction (XRD) aided by the refinement method of Rietveld allowed phase quantification and determination of the spinel lattice parameter (8.464± 0.005 Å). A reaction pathway is put forward based on a thermal analysis using simultaneous thermogravimetric analysis and differential scanning calorimetry (TGA/DSC). The proposed mechanism suggests that spinel is formed by the reaction between SnO 2 (formed from SnCl 4) and CoO which in its turn is produced during the decomposition reaction of Co 3 O 4 into CoO and O 2 . Co 3 O 4 on the other hand, is formed previously from Co(NO 3) 2 .
Journal of Food Science, 2012
Industrial & Engineering Chemistry Research, 2013
ABSTRACT Injection molding is a process employed worldwide to manufacture polymer parts. The fina... more ABSTRACT Injection molding is a process employed worldwide to manufacture polymer parts. The final properties of the molded part largely depend on the processing conditions used during the manufacturing process. Therefore, it is necessary to develop empirical approaches that help to understand the relationship between the processing conditions and the final properties of the polymer. In this paper we study the effect of the processing conditions of the injection molding process on the Young?s modulus of a low-density polyethylene (LDPE). The effect of both the barrel temperature and the mold temperature was investigated using analysis of variance (ANOVA) and the effect of the levels of each parameter was examined using the surface response methodology (SRM). The ANOVA results showed that the mold temperature is the parameter that most significantly impacts the Young?s modulus, followed by the barrel temperature, while the combined interaction of both is negligible. SRM showed that the Young?s modulus increases with the mold temperature and decreases with the barrel temperature. Based on the SRM, an empirical equation is proposed which can be used to predict the modulus employing only the barrel and mold temperatures. The changes in the microstructure of the injection molded part are discussed in terms of the crystallinity degree. All this was corroborated with X-ray diffraction (XRD) and differential scanning calorimetry (DSC).
CyTA - Journal of Food, 2012
Measuring glass transition temperature is necessary for predicting the state and the behavior dur... more Measuring glass transition temperature is necessary for predicting the state and the behavior during the processing, distribution, and storage of many amorphous sugar-rich products. Therefore, the purpose of this study was to establish an improved calorimetric methodology to assess T g in amorphous sugars. This method was created through melting crystal with differential scanning calorimetry (DSC) using the same principle proposed by Jiang, Liu, Bhandari, and Zhou (2008. Impact of caramelization on the glass transition temperature of several caramelized sugars. Part I: chemical analyses. Journal of Agricultural and Food Chemistry, 56, 5138-5147). Thermogravimetric analysis with simultaneous DSC was required to characterize the melting and thermal degradation temperatures of sugars. Thermograms showing the complete process of heating-cooling-reheating are proposed to determine the precise glass transition temperature during cooling (T gC) or reheating (Tg H), and to verify if the processed amorphous samples were created with or without thermal degradation. The melting temperature has little effect on the T g value whereas the sugar was melted without thermal degradation. Thus, using this methodology the precise T g value of amorphous sugars can be determined.
Applied Catalysis B: Environmental, 2013
Molecules
This research presents the microencapsulation and conservation of antioxidants of broccoli juice ... more This research presents the microencapsulation and conservation of antioxidants of broccoli juice processed by spray drying, and proposes the use of a by-product as a technological application. Broccoli juice (BJ) extracted from two sources, stalks and florets, was spray-dried employing maltodextrin (MX) as a carrier agent at concentrations of 5, 7.5, and 10%, and inlet temperatures of 150 and 220 °C. The total phenolic content (TPC), and antioxidant activity (AA) of the BJ-MX powders were determined together with the physicochemical characteristics, including particle morphology, microstructure, and thermal properties. Based on the TPC and AA, the optimal processing conditions found were 5% of MX and a drying temperature of 220 °C. However, the florets showed higher TPC, while stalks presented higher AA under those processing conditions. The particles exhibited micrometric sizes and a mixture of spherical-shape particles and pseudo-spherical particles. The diffractograms indicated a...
Molecules
The drying of fruit juices has advantages such as easy handling of powders, reduction in volume, ... more The drying of fruit juices has advantages such as easy handling of powders, reduction in volume, and preservation of the characteristics of the fruit. Thus, in this work, the effect of the spray drying conditions of strawberry juice (SJ) with maltodextrin (MX) as a carrying agent on the microencapsulation of bioactive compounds and physicochemical properties was studied. The content of phenolic compounds and antioxidant activity showed higher values at low concentrations of MX, while the effect of drying temperature was negligible. The thermal characterization showed that the low molecular weight sugars in the juice decreased the glass transition temperature (Tg). The morphological analysis by scanning electron microscopy (SEM) indicated that at low concentrations of MX, the particles agglomerated, while at intermediate and high concentrations, the particles were observed as well separated. Through microstructural analysis by X-ray diffraction (XRD), the presence of amorphous state ...
Polymers, Feb 13, 2019
The influence of the processing conditions during the spray drying of mixtures of blueberry juice... more The influence of the processing conditions during the spray drying of mixtures of blueberry juice (BJ) and maltodextrin (MX) was determined quantitatively by the analysis of variance (ANOVA), and qualitatively by the surface response plots (SRP). The effect of two independent variables (inlet temperature, and MX concentration), and one categorical variable (type of MX), was determined on the yield (Y), content (Q), and retention (R) of the antioxidant quercetin 3-D-galactoside. From the ANOVA results, the concentration was the main variable affecting Y and Q, while temperature had a negligible effect, and the low molecular weight MXs exhibited a better response. The physicochemical characterization showed that the powder appearance and microstructure remained unaffected, but size and morphology of the particles varied with the processing conditions. This study established the optimal processing conditions for the spray drying of BJ-MX, and the application limits of the MXs based on the molecular weight distribution.
In this work is presented the complete thermal analysis of polyols by direct methods such as simu... more In this work is presented the complete thermal analysis of polyols by direct methods such as simultaneous thermogravimetric and differential thermal analyzer (TGA-DTA), differential scanning calorimetry (DSC), modulated DSC (MDSC), and supercooling MDSC. The different thermal events in the temperature range of 113–553 K were identified for glycerol (GL), ethylene glycol (EG), and propylene glycol (PG). Boiling temperature (T B) decreased as GL > EG > PG, but increased with the heating rate. GL showed a complex thermal event at 191–199 K, identified as the glass transition temperature (T g) and devitrification temperature (T dv), and a liquid–liquid transition (T L-L) at 215–221 K was identified as the supercooling temperature. EG showed several thermal events such as T g and T dv at 154 K, crystallization temperature (T c) at 175 K, and melting temperature (T m) at 255 K. PG also showed a complex thermal event (T g and T dv) at 167 K, a second devitrification at 193 K, and T L-L at 245 K. For PG, crystallization was not observed, indicating that, during the cooling, the liquid remained as an amorphous solid.
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Papers by Alberto Toxqui Terán